import java.util.Stack;

public class solution {
    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<>();
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            if (ch == '(' || ch == '[' || ch == '{') {
                stack.push(ch);
            } else {
                if(stack==null){
                    return  false;
                }

            }
          char topL=stack.peek();
            if(topL=='('&&ch==')'||topL=='['&&ch==']'||topL=='{'&&ch=='}'){
                stack.pop();
            }else {
                return false;
            }


        }
        if(!stack.isEmpty()){
            return false;
        }
        return true;
    }
}
